Websites need to be accessibility-conscious for ease of use for people such as the visually impaired, so that some countries and international organizations specify official standards. Conventionally, to improve the accessibility of low-accessibility web pages, the pages themselves need to be modified. However, it is known that the accessibility improvement cost can be significantly reduced by dynamically modifying, with external metadata (hereinafter simply referred to as metadata), DOM of pages being viewed on a browser. This metadata is generally enabled for a plurality of pages by expressing, using a regular expression, a pattern representing URLs of content to which the metadata is applied. As a result, the application range of the metadata can be extended to reduce the number of pieces of metadata to be created. In another instance, when a new page is added, any existing metadata that is applicable can be used to improve the accessibility of the page without creating new metadata.
Generally, creating and managing metadata for a website takes the following procedure. (1) The website is crawled. (2) DOM of obtained pages is analyzed. (3) Based on the result, a metadata creator creates metadata for an arbitrary page. (4) The metadata is extended to be applicable to a plurality of pages with the aid of a tool. (5) The accessibility of each resulting page with the metadata applied thereto is verified. (6) The metadata is actually distributed to visually impaired people. Published Unexamined Patent Application No. 2003-85087 and Published Unexamined Patent Application No. 2004-14594 disclose prior art of aiding in this metadata creation and extension. The Published Unexamined Patent Application No. 2003-85087 allows automatically generating the metadata application range by analyzing the layout of a page and by generating a normal expression of URLs corresponding to pages with similar layouts. The Published Unexamined Patent Application No. 2004-14594 allows aiding in checking and editing the metadata application range by using a UI that provides a list indicating which piece of created metadata is applied to which page.
However, the conventional techniques have the following problems with the steps (3), (4), and (5). That is, in the step (3), the metadata creator arbitrarily chooses a page for which the metadata is to be created. If several persons simultaneously create the metadata, the respective metadata application ranges may overlap each other in (4) and overlapping pieces of metadata may be created in the entire website, resulting in inefficient metadata creation. Also in the step (4), the technique of the Published Unexamined Patent Application No. 2003-85087 allows extending the metadata to pages with similar layouts, and the user interface of the Published Unexamined Patent Application No. 2004-14594 allows viewing a list indicating to which page each piece of metadata is applied. However, these techniques do not take into account whether each piece of extended metadata is applied as intended. Therefore, the metadata creator cannot know information such as a high likelihood of inappropriate metadata application. Furthermore, in the step (5), the conventional techniques do not take verification into account as to whether the accessibility of pages with the created metadata applied thereto has actually improved. Since verifying all pages is not realistic, some pages may be chosen and verified. However, if a verifier chooses and verifies arbitrary pages, the verifier may leave some metadata unverified or miss verifying pages likely to have metadata incorrectly applied thereto. Thus the effectiveness of the metadata cannot be efficiently verified.